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Messages - krypton

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1
Just a note to tell you why I did not use Chris's circuit directly.  I did not need an external supply, because there was one directly available in the spindle motor drive inverter, with its own analogue earth, for a potentiometer input.  To get the maximum speed the voltage has to range right up to (usually) 10V.  Hence I needed a low resistance drive and a low resistance in the filter.  In my case the potentiometer input resistance was 20K, so that was the load on the filter.  As it turned out the internal power supply was 10.2V, giving me some head room, and it worked out fine - I could get the full speed from the spindle.

So I was then happy to further load the logic chip with the extra filter to drive the forward pin.  I was also happy to use the internal power supply analogue earth for the common, where I should have used the digital earth for this digital signal.  I could get away with this because it is a steady load on the speed signal for the full time of when the spindle is spinning.  If any other digital input loaded the circuit it could alter the speed slightly when active.

And I required optoisolation.

A further note.  There are many thousands of transistors, all with similar specifications.  So it generally does not matter what transistor is used.  Voltage and current rating are important, but for small signal transistors your use will be well below the limits.  FETs have different abilities than bipolar, and there are npn, pnp, n-type and p-type specs that you must get right.

Similarly resistors have voltage and power maximum ratings and capacitors have maximum voltage ratings.  But again you are likely using them well below their maxima.  The same is true for logic gates.  We could have used any NOR, NAND or NOT gates available, because we are using the chip only as an inverter.  Subject to their maximum voltage rating as already noted.

Krypton

2
Krypton.
I built Chrisjh circuit some time ago but never got around to fitting it into my system, This thread has spurred me into action. I noted your comments about opto isolator of the circuit from the PWM on pin 14. With your opto circuit you say to omit the resistor & transistor in Chrisjh circuit. On my BOB the PWM from pin 14 is already opto isolated so do I just connect this and ground to the I/p & ground of the  4011N ( ie omit R4 & TR1)
Thank you.
Ian

Yes, you must wire it without R4 and T1, direct into the logic chip.  In Chris's circuit he needed to amplify the voltage from TTL levels to the 12V.  His circuit can also handle 5V inputs, that are more common these days.  The transistor also inverts the signal, and you should get the same inversion through the opto-isolator, depending on how it is wired.  There are spare inverters in the 4011, or you can change the polarity in Mach3.
 
Krypton

3
right, you have pulses at the input.  Now check the circuit as I have listed.  You don't need the oscilloscope,  just the on/off signal you have been using so far.

There are two signal inversions, one through the optoisolator and the other through the logic chip.

Krypton

Krypton,

I am not an expert so at first I am making the circuit without the opto-isolater(just sticking to the schematics for troubleshooting). Looks like there might be something else which may have gone wrong.  Can this be the problem that I am using capacitors of capacity 10uF 63volt and 100uF 25volt against 10uF 16volt and 100uf 16volt ?? Also I have connected 12volt to pin 14 and GND to pin 7 of 4011 IC, is this to be done or not? These are the gray areas which might be causing trouble as per my brain works.

The maximum voltage rating of the capacitors will make no difference.  It must exceed the applied voltage, in this case 12V.

And you are correct that the 4011N pin 14 should be connected to +12V and pin 7 to GND.  If you are not using the N-type (dual-in-line) check the specs for your chip.

In Chris's circuit he had lines to the chip, with no numbers, which in this case he should have added.  Professional engineers sometimes have a shorthand, and often neglect to detail the power connections, in the interests of clarity of operation of the logic.

I said in a previous post that some logic chips are designed for use on 5V supplies, and cannot handle the 12V.  So check that the chip you are using is the correct one.  The easiest way is to google the exact chip name that is printed on the chip you have, and look for the absolute maximum part of the specification.  You will need 16 or 18 V versions.

My apologies for not replying promptly - I am in a very different time zone, GMT+13.

Krypton

4
right, you have pulses at the input.  Now check the circuit as I have listed.  You don't need the oscilloscope,  just the on/off signal you have been using so far.

There are two signal inversions, one through the optoisolator and the other through the logic chip.

Krypton

5
Fired the circuit but looks like I messed up, there is no analog output coming from it, so gonna assemble a new circuit keeping in mind the schematics, hope for the best

Cheers

==========
It should be very easy to debug.  There should be pulses on the new circuit input (the output from the breakout board).  If you do not have access to an oscilloscope, then an old-style analogue voltmeter would be better that a digital meter because it has inherent mechanical filtering.

So you should be able to control the voltage on the circuit input by controlling the speed through Mach3.  Then look at the optoisolator output (the logic chip input), the logic chip output, the filter output - in turn.

I would expect that your problem is that Mach3 is not yet producing pulses.

Krypton

6
On this Lathe (TCL150) the way the tool turret and tools are designed the Surfacing tools come into contact with the workpiece from above. This is where the reverse rotation of the spindle motor is needed.

I assume also that accurate control of the spindle speed is required where 'Threading operations' are carried out ?

==========
Of course.  If you always use reverse then my Krypton extra circuit would work.  If you require both forward and reverse, then the G-code solution would be best - that I cannot advise on.

Inherent in the PWM filtering is a ripple on the DC.  I adjusted the values of the filter (R, R*C) and the PWM period as a compromise to achieve satisfactory operation.  In our spindle driver there is an output when the speed is stable, and it showed that the speed was continuously hunting - trying to follow the ripple.  But the motor sounded fine, so it is a reasonable compromise.

Krypton

7
Len-Tikular wrote:
I could use some help please in hooking up my Spindle motor to my breakout board.
This is ongoing from my conversion of my TCL160 which has a Mitsubishi FR-Z024 0.37k fitted.

The original Documentation from the TCL160 shows these connections were used.

STF (Fwd) to pin 5 on my new board
STR (Rev) to pin 7 on  my new board
5
2
P24 (Looks like pin SD which is common) Output shutoff, how is this handle by Mach3
MRS/RT This is marked as 'Boost' on the original TCL Manual (What is the purpose of the Boost)

============
I am doing some guessing here.  

I have not learned how to control the forward from Mach3, because it would require a motor on/off inserted in the right places in the G-code.  I am sure it is possible.  That is why I added the extra circuit, filtering the PWM signal, so it is in forward mode only when the PWM pulses are present.

The FRZ-024 manual shows that there are two ways to control the speed.  One is with three wires (RL, RM, RH), providing slow, medium and high speed.  The other is a potentiometer (pins 10, 2, 5) that gives a speed proportional to the voltage on the slider.  This would be best, so I suggest my Krypton circuit as above (reply 23) to give both speed and forward signals.  There is an internal +5V supply (pin 10) to power the filter circuit, and the same constraints are needed - a low value filter resistor to provide the full range from the internal +5V with the filter driven hard from a low resistance driver chip.  Use pin 5 as the common ground for this circuit, not the digital ground P24.  See Appendix B in the manual.

I cannot envisage a need for reverse motor direction, so you will not require that input at all.

I think that the second acceleration/deceleration (MRS) would be for emergency stop conditions, a safe fast stop, not a dead stop, which may put more stress on the motor than is justified or safe.  Remember that these controllers are not only used for NC milling, etc. (I worked on locomotives, and if they are stopped too quickly they can derail, or put flats on the wheels - there is an optimum deceleration.)

Krypton

8
To the common ground of the breakout board - the computer ground.  Because there are two grounds that are not connected, they have to have different names.

Krypton

9
Sorry, one picture is worth a thousand words.
Krypton


10
Practically any opto-isolator will do, as the PWM pulses are not fast.  I used a HCPL-0501 because I had it in stock.  I drove the opto-isolator internal LED direct from the break-out board through a 470 ohm resistor (into pin 3).  The output transistor (pin 6) has a 22K load to +10V, into the hex inverter inputs.  Pin 8 to +10V, pin 2 breakout board earth, pin 5 the motor controller earth  See my last posting - Sep 9, 2014.

You cannot use a solid state relay because they are a latch, and normally are only used for switching AC - they depend on current reversal to turn off.

Krypton

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